Table 2. Assessment of the risk of bias (appraised with the MMAT).

Quantitative descriptive studies	Ahmed et al. (2017)	Catteeuw et al. (2010)	Elsworthy et al. (2014)	Emmonds et al. (2015)	Gomez-Carmona and Pino Ortega (2016)	Mallo et al. (2012)	Oudejans et al. (2005)
Is the sampling strategy relevant to address the research question?	1	1	1	1	1	1	1
Is the sample representative of the target population?	1	1	1	1	1	1	1
Are the measurements appropriate?	0	0	0	0	0	0	0
Is the risk of non-response bias low?	0	0	0	0	0	0	0
Is the statistical analysis appropriate to answer the research question?	1	1	1	1	1	1	1
Quantitative non-randomized studies	Larkin et al. (2014)	Mascarenhas et al. (2009)	Paradis et al. (2015)	Samuel et al. (2019)
Are the participants representative of the target population?	1	1	1	1
Are measurements appropriate regarding both the outcome and intervention (or exposure)?	1	1	1	1
Are there complete outcome data?	1	1	1	1
Are the confounders accounted for in the design and analysis?	1	1	0	0
During the study period, is the intervention administered (or exposure occurred) as intended?	c	c	c	c

*Legend: 1 = yes, 0 = no; c = can’t tell